1. Field of the Invention
The present invention relates to apparatus and a method for cooling a clutch of a motor vehicle utilizing a valve through which a coolant circuit can be coupled with a pump circuit.
2. Description of the Related Art
Apparatus and a method for cooling a clutch of a motor vehicle are known in the field of automotive technology. The known apparatus is a system that has two valves. A first valve is connected to a return conduit and to a supply conduit of the coolant circuit that is used for cooling the clutch. Additionally, in the known system a second valve in the form of a minimum pressure valve is necessary. The minimum pressure valve is coupled to the valve for cooling the clutch and to a pump circuit. Because the minimum pressure valve is needed to actuate a predetermined pressure, a corresponding backpressure arises in the coolant circuit.
The function of the valve for cooling the clutch is to control the flow of coolant to the clutch. In the known system the minimum pressure valve prevents air from entering the suction section of the pump for the pump flow through the return conduit of the coolant circuit during the start-up phase, which would prevent oil from being delivered from a supply tank. In addition to the disadvantage due to the occurrence of the backpressure in the coolant circuit described earlier, the known system has the further disadvantage that a larger construction space is needed because of the two necessary valves.
Published patent specification DE 10 2004 005 790 A1 discloses a control, in particular a hydraulic control, having a directional valve to control a cooling system for a clutch and to ensure a suction function of a pump.
In the known control, it is absolutely necessary that the directional valve includes two control pistons in order to achieve the cooling of the clutch and also the suction function of the pump.
Accordingly, an object of the present invention is to propose apparatus and a method for cooling a clutch of a motor vehicle with a valve of the type named at the beginning, with which both the cooling function and the suction function can be ensured in every phase of operation, and in addition an especially compact and space-saving type of construction is achieved.